The very first question to ask is what are "conflict diamonds"? The definition by the United Nations reads: "...diamonds that originate from areas controlled by forces or factions opposed to legitimate and internationally recognized governments…" You might then think that there are probably all sorts of minerals or resources in areas of such conflict, such as: oil, plutonium, phosphorus, titanium, and so on and so forth, so is somewhat puzzling why diamonds should be something that is of particular concern, as opposed to these other natural resources and minerals.
The basic answer to that question is that diamonds, unlike many other resources have been essentially price-controlled by the De Beers cartel for years, so that the very best thing for any cartel that wants to sustain itself is to declare that diamonds that are procured from other areas of the world, in particular those are outside De Beer's sphere of influence, are somehow tainted, so that in essence, because those diamonds are tainted, De Beers subsequently is still able to command a premium for their diamonds, knowing that they need not have to worry about being undercut.
Another important issue, is De Beers, itself, in which De Beers is by far the biggest producer of diamonds in South Africa, a country that was known for decades for its policy of apartheid, which was considered an anathema to the international community, and although, apartheid has come and gone, De Beers still remains, though De Beers has historically not been noted for its liberal conditions towards blacks, but rather has been seen at best as employing blacks in the grunt and dangerous work of the actual mining, and at worse, just outright exploitation.
All of the above points to the very obvious concern, which is, why does a company such as De Beers get a free pass, as if they have never been guilty of essentially taking the lion's share of profits for themselves, their stockholders, and their board of directors, while in return providing native South Africans with nothing even approaching the wealth that has been successfully extracted from South African soil by De Beers essentially running and dominating the show, in which not even the elimination of apartheid, fundamentally changed the nature of De Beers business or control.
To say that diamonds should be divided into conflict and non-conflict diamonds might make good copy, but in reality, the great bulk of diamonds that are mined in Africa are mined by black hands, while the real beneficiaries of these diamonds are white hands and white capital, but somehow that story is completely ignored, in favor of some sort of arbitrary distinction that diamonds that are mined in countries that are not in revolt are legitimate because they are considered to be blood-free diamonds, but the reality of it is that virtually all African diamonds are essentially mined by the sweat, bodily risk, and toil of black inhabitants that receive in return a small fraction of the worth of the diamonds so mined.
Diamonds are an expensive luxury item, in which the maintaining of pricing, distribution, and control are essential for maximizing such, so by controlling the narrative so that those that are outside your realm, are thereby designated as illegitimate because they have been branded as "conflict diamonds" this, in essence, becomes just a devious way to put a spike into your competition.